Microdispensing pumps are known in the prior art, such as those disclosed in U.S. Pat. No. 5,881,956; WIPO PCT Published Application No. WO 01/14245; and related applications. The entire disclosures of these references are incorporated by reference herein.
Although microdispensing pumps are known in the prior art, problems still exist with their operation and storage. For example, with a microdispensing pump used in an ophthalmic application, ingress of dirt into the pump's nozzle is a major concern. With prior art eye dropper bottle designs, a threaded overcap is typically provided which is formed to sufficiently thread onto a dropper bottle body to press against and form a tight mechanical seal against the dispensing aperture of the dropper bottle. However, with a microdispensing pump, such a design is not practicable, because of the nozzle orientation (i.e., being transverse to the longitudinal axis of the pump body), as well as, the simple fact that movement of the nozzle, vis-á-vis the dispensing cap, may result in inadvertent actuation of the pump. With eye dropper bottles, tight contact between an overcap and a dispensing aperture does not result in an inadvertent administration of fluid.